A 9 year-old female is carried into your acute care center by her parents who state that the patient “suddenly fell out.” You observe an unresponsive, 36 kg female, breathing easily at a rate of 28 per minute. There is no sign of increased work of breathing. The peripheral pulses are weak and are palpated at a rate greater than 250 per minute. Capillary refill is greater than 5 seconds. The parents deny any past trauma or medical history, and have no idea what is happening.